A term students used in the 1990s. It's probably an evolution of the simular colloquialism browner.

Someone that is very smart and seems to excel at everything. The type that always seems to have some new project that requires exceptional intelligence to even plan, let alone implement.

The type a student will go to when they need serious help with a test/exam or project for a class they're doing poorly in. Although some may explain said subject in a way that that will have the person requiring help saying ‘in English please’, once they’re able to get on the same level with the person, a brainer can be a very valuable study buddy.
Person #1: Did you hear? Billy got Jimmy to be his partner for the big term assignment!

Person #2: Really? That lucky dog; Jimmy is a major brainer. With him as his partner, Billy is practically guaranteed an A!
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His video timer is such a brainer that he is leaving it flashing at 12:00 AM.
by Milt Alwin March 20, 2009
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noun. A person (particularly a female) who will gladly accept head but wont return the favor. Most commonly technical virgins who aren't yet accustomed to much sexual behavior. (Or simply just a prissy bitch)
Kenny: Hey you know any females that give good head?
Eli: Ohhh! how bout Jessica? Dude, I heard that girl swallows!!!
Kenny: wtf? Oh hell naw man she's definetely a no brainer. and her dad's a cop..you got me fucked up dawg.
by jajkbnkn January 23, 2011
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Somone who is smart funny and fun to be around and used to trick people to think ur talking bout giving head
man i love to be around that girl shes a brainer
by gtman43 April 1, 2010
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A brainer in when a person inhales marijuana smoke through their nose, sending it straight to the brain.
"Hey man, you wanna toke?"

"No, I'll just take a quick brainer!"
by Kanuckilish March 10, 2009
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Old trainers, where the front has worn down giving the appearance of a throbbing brain.
Haha check out his brainers!
by Lewis1983 May 30, 2005
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A girl who won't perform oral sex.
She's cool and all, but she's a no-brainer, so you'll have to settle for an old-fashioned.
by cuban April 26, 2005
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